A large number of sex differences have been described in the mammalian central nervous system. Such morphological dimorphisms may underlie well-documented sex differences in behavior, in susceptibility to certain drugs, and in the incidence of human neurological disorders. In many cases, neural sex differences have been shown to be due to gonadal steroid hormones acting early in development. However, the cellular and molecular mechanisms governed by hormones in the developing nervous system are not well understood. The long-range objective of this candidate for an Independent Scientist Award is to identify cellular and molecular mechanisms of sexual differentiation in the brain and spinal cord. Dr. Forger is a professor in the Psychology Department at the University of Massachusetts. She is a member of the Neuroscience and Behavior program and enjoys the support of a cohesive and very visible group of colleagues in the Center for Neuroendocrine Studies. The candidate will soon be directing several major research efforts. Her teaching load within the Psychology Department is substantial. The award will allow her time to intensively focus on funded projects, to interact more with trainees and colleagues, and to pursue new areas of research. In particular, this award will support training in confocal microscopy and molecular biological techniques. The research plan outlines strategies for investigating the mechanisms underlying hormonally controlled cell death in three well-studied model systems: the spinal nucleus of the bulbocavernosus, the anteroventral periventricular nucleus of the hypothalamus, and the bed nucleus of the stria terminalis. Mice will be used throughout, to take advantage of the power of genetically manipulated strains. An R01 proposal describing these studies was recently reviewed and received outstanding priority ratings. An Independent Scientist Award would ensure the success of this program.